. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. Fig. 301.—Diacrisia. Section through head at stomodaeum (stom). (am) Amnion. At 42 hours (Fig. 297C) the two anteriorly directed cephahc pouches so prominent in earlier stages (Figs. 297A,B) are still present, though they have become smaller and shallower. Just posterior to their dividing wall may be seen a mass of cells of the inner layer which in the middle is abdIO stom md abd9. Fig. 302.—Diacrisia. Long
. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. Fig. 301.—Diacrisia. Section through head at stomodaeum (stom). (am) Amnion. At 42 hours (Fig. 297C) the two anteriorly directed cephahc pouches so prominent in earlier stages (Figs. 297A,B) are still present, though they have become smaller and shallower. Just posterior to their dividing wall may be seen a mass of cells of the inner layer which in the middle is abdIO stom md abd9. Fig. 302.—Diacrisia. Longitudinal section (slightly oblique frontal) of 48-hour embryo, {ab 1-10) Abdominal segments 1 to 10. {am) Amnion, {lb) Labium, {md) Mandible, {mx) Maxilla, {stom) Stomodaeum. {th) Thoracic segments. four or five cells thick (Fig. 300A). Posteriorly, it is continued as a median band a number of cells in width. Two hours later there is anterior to this mass in the head an inner layer one cell in thickness. Neither stomodaeun nor proctodaeum is as yet in evidence. At this. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Johannsen, O. A. (Oskar Augustus), 1870-1961; Butt, Ferdinand Hinckley, 1899-. New York, London, McGraw-Hill Book Company, inc.
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